Microwave oscillator and detector



May 9, 1939.

E. G. LINDER MICROWAVE OSCILLATOR AND DETECTOR Original Filed July 2, 1954 Tl l l l l h fi i 2% 3nnentor Erziest G. Linder (Ittorneg Patented May 9, 1939 MICROWAVE OSCILLATOR AND DETECTOR Ernest G. Linder, Philadelphia, Pa., assignor to Radio Corporation of America, a corporation of Delaware Original application July 2, 1934, Serial No. 733,381. Divided and this application May 16, 1936, Serial No. 80,110

15 Claims. (Cl. 250-275) This invention relates to means for generating, modulating and demodulating high frequency oscillations and particularly oscillations of ultra short wave length.

This application is a division of my copending application Serial No. 733,381, filed July 2, 1934, which issued February 16, 1937 as United States Patent No. 2,071,311.

I have found that, when working with microwave lengths, that is with waves of less than a meter and down to a few millimeters in length, a very eificient and stable oscillator may be provided in which the tuned oscillator circuit is entirely comprised within the envelope of either a Barkhausen-Kurz tube or a magnetron type electron discharge tube. The envelope of such a tube may also contain both the transmission line and the antenna, if desired. It is, however, within the scope of my invention to provide oscillating means for ultra short wave radio transmitting and receiving apparatus having an antenna outside of the evacuated envelope.

It is an object of my invention to provide an oscillation generator or detector suitable for ultra high frequency transmitting and receiving apparatus.

Another object of my invention is to provide a magnetron type high frequency oscillator having split anode units suitably disposed within an evacuated envelope and suitably interconnected so that a resonant circuit .is obtained entirely within the envelope itself.

The foregoing and other objects of my invention will be more fully understood from the following detailed description when read in connection with the accompanying drawing, in which Figure 1 is a View showing in perspective one embodiment of my invention comprising a tuned oscillator circuit including split anodes of a Barkhausen-Kurz type tube,

Fig. 2 is a view in perspective of a magnetron type tube comprising an oscillating loop in which the included split anodes are integral with a heavy conducting ring, and

Fig. 3 is a perspective view of a Barkhausen- Kurz oscillator which includes the heavy conducting ring anode.

Referring to Fig. 1, I show an envelope l and base 2 of usual construction. A pair of split anodes 3 is mounted on stiff wires 4 which project through the top of the tube. These wires may be elongated to provide a transmission loop connecting with an antenna 5. A shorting bar 6 is welded across the wires 4 within the envelope I and preferably so close to the anodes 3 that standing waves of the operating frequency and having one nodal point midway of the bar 6 may be produced thereon. A filament cathode 'l is shown at the axis of the semi-cylindrical anodes 3. Supporting posts 8 for the filament are mounted on the press 9 and are connected with the tube prongs l0. A control grid 35 is disposed between the cathode and anodes. It is supplied with a high potential from the source 36. Filament current may be derived from the source II. By means of a source 12 a potential slightly greater than that of the filament but considerably below that of the grid is applied to the anodes, connection to which is made through the choke Hi, the antenna 5 and the transmission wires 4.

The shorting bar 6 together with the portions of the transmission wires 4 intervening between the shorting bar and the anodes 3 form a resonant loop which determines the natural frequency of the oscillator. The energy of the oscillations thus produced is more or less efficiently communicated to the antenna 5, from which it may be radiated as a carrier wave. carrier may be modulated by means of audio frequency currents impressed upon the transformer T, thus varying the potential applied to the grid 35.

In Fig. 2 I have shown a construction of magnetron type oscillator tube comprised within an envelope l and having a unitary structure of split anodes 3| the faces of which are in effect the cylindrical walls of a hole drilled in a metallic ring IT. This bifurcated ring is supported by transmission wires 4 issuing at the top of the tube, the same as shown in Fig. l. The filament cathode l is also of the same construction as in Fig. 1. This tube requires no grid because it operates in a magnetic field which is produced by magnetic pole pieces 40, and 4!, or the like. Other details of the tube correspond with the details already described in connection with Fig. 1 and need not be specifically mentioned at this point.

The modification of my invention shown in Fig. 2 is particularly well adapted for operation at ultra high frequencies, even down to a few millimeters of wave length. It will be seen that the bifurcated ring ll affords a very short resonant path for such waves. On the ring and diametrically opposed to the axis of the electrodes a node will be formed. The transmission wires 4 are connected to one side and the other, respectively, of said node.

The

A suitable circuit diagram has been included in Fig. 2 so as to illustrate the utility of the tube either as an oscillator or as a detector. The transformer T, whose winding I3 is in the anode circuit, may have impressed upon its winding l6 a modulation current from any desired source. This serves to vary the potential applied to the anodes 31. If, however, the tube is to be used as a detector, the electrode potentials having been suitably adjusted to prevent oscillation, then the current in the plate circuit (Ip) will be varied by the received signal voltage impressed upon the anode (E11) and demodulated, energy will be derived from the transformer coil Hi. When the three-element tube of Fig. 1 is operated as a detector variations in the, plate voltage (Ep) effect a corresponding change in current flowing in the grid circuit (Eg).

The output coupling device T of Figs. 1 and 2 may be of any convenient type adapted to match the-impedance of the tube with the impedance of the apparatus associated therewith.

Fig. 3 illustrates the application of the heavy ring-shaped anode to the Barkhausen-Kurz tube. The reference numerals are applied to parts corresponding to the preceding figures so that a detailed description of this figure is believed not to be necessary.

It will be readily understood by those skilled in the art that any of the embodiments of my invention herein shown may be used as a short wave oscillator or as a detector. The antenna may be disposed either internally or externally of the evacuated envelope. End plates may be used in any case. If end plates are not used then the axis of the electrodes should be at a slight angle to the polar axis of the magnetic field in which the magnetron tube operates. If the tube is of the three-element type, for instance, as shown in Fig. 1 no magnetic field need be supplied. To obtain the specified results with tubes of the two-element type, with or without endplates, or with the three-element type having end-plates, the tube is necessarily immersed in a magnetic field.

Although I have disclosed herein several modifications of my invention and have described a method of generating oscillations of ultra high frequency, it is to be understood that the foregoing description is merely illustrative of many ways in which my invention may be carried out. Other modifications will suggest themselves to thoseskilled in the art. My invention, therefore, is not to be limited except insofar as is necessitated. by the prior art and by the spirit of the appendedv claims.

I claim as. my invention:

1. An electron discharge device including an evacuated envelope, a conductor disposed within said envelope and terminating in split anode electrodes, said conductor having a cross sectional area of the order of the area ofone of said anode surfaces, and a cathode disposed sub stantially parallelv to said anode surfaces.

2. An electron discharge device including an evacuated envelope, a conductor within said envelope terminating in split anode electrodes having surfaces of substantially concave semicylindrical form, said conductor having a cross sectional area of the order of the area of one of said anode surfaces, and a cathode disposed substantially on the axis of said semi-cylindrical anodes.

3. An electron discharge device including in combination an evacuated envelope, a conductor located within said envelope, said conductor terminating in split anodes having a combined surface substantially equal to twice the cross sectional area of said conductor, and a cathode disposed between said anodes.

4. An electron discharge device comprising an evacuated envelope, a bifurcated metallic ring mounted in said envelope, a pair of split anodes being formed within the bifurcation in said ring, and a cathode disposed parallel to the terminal surfaces of said ring formed by said bifurcation.

5. An evacuated envelope, a conductor located within said envelope and terminating in split anode electrodes, said conductor having a cross sectional area of the order of the area of one of said anode electrodes, a cathode disposed substantially parallel tosaid anode electrodes, and a pair of transmission Wires supporting said conductor and forming conductors for high frequency currents generated in said conductor.

6. An electron discharge tube comprising an evacuated envelope, a bifurcated metallic ring disposed within said envelope, a pair of split anode electrodes being formed by the bifurcation in said ring, a cathode disposed within the bifurcation in said ring, and a pair of transmission wires supporting said ring and connected to said ring at points intermediate the split anodes.

7. An electron discharge tube comprising an evacuated envelope, a conductor disposed within said envelope, said conductor terminating in split anode surfaces formed by concave surfaces in the terminals of said conductor, and a cathode disposed substantially coaxial with said anode surfaces.

8. An electron discharge tube comprising. an evacuated envelope, a conductor disposed within said envelope, said conductor terminating in split anode surfaces formed by concave surfaces in the terminals of said conductor, a cathode disposed substantially coaxial with said concave surfaces, and a transmission line connected to and. supporting said conductor.

9. An electron discharge device including an evacuated. envelope, a conductor disposed within said envelope and terminating in split. anode electrodes, said conductor havinga cross sectional area of the order of the area of one of said anode surfaces, a cathode disposedsubstantially parallel to said anode surfaces, and av control electrode disposed around said cathode.

10. An electron discharge device comprising an evacuated envelope, a bifurcated metallic ring mounted in said envelope, a pair of split anodes being formed by. the bifurcation in. said ring,. a cathode disposed parallel to the terminal surfaces of said ring formed by said bifurcation, and

a control electrode disposed around said cathode.

11. An evacuated envelope, a conductor located within said. envelope and terminating in. split anode electrodes, said conductor having across sectional. area of the order of' the area of one of-said anodeelectrodes, a cathode disposed sub stantially. parallel totsaid'anode electrodes, a pair of transmission wires supporting said conductor and forming conductors for high frequency currents generatedinsaid-conductor, and a control electrode disposed around said cathode.

12. An electron discharge device including an evacuated envelope, a, conductor disposed within said envelope and terminating in split anode electrodes, said conductor having a cross sectionalarea. of. not less than the projected. area.

of one ofsaidanode surfaces, anda cathode dis.-

nitude, said arms terminating in juxtaposed surfaces separate from the boundaries of said cavity, and another electrode between said juxtaposed surfaces.

15. A magnetron comprising a substantially 5 cylindrical anode having portions bounding a substantially cylindrical cavity and terminating in juxtaposed arcuate surfaces, a cathode disposed between said arcuate surfaces and coaxial therewith, and means for producing a magnetic 10 field in the vicinity of said cathode.

ERNEST G. LINDER.

CERTIFICATE OF CORRECTION. Patent No. 2,157,179.' I may 9, 19 9.

ERiIEsT G. LINDER.

It is hereby certified that errorappears in the printed specification of the above numbered patent requiring correction as follows: Page 2, econd column, line 9, claim h, for the word "within" read by and that the saidfiLetters Patent shouldbe read with this correction therein thatthe same may conform to the record of the case in the Patent Office.

Signe d and sealed this 16th day of January, A. D. 191 0.

Henry Van Arsdale',

(Seal) Acting Commissioner of Patents. 

